RESUMO
BACKGROUND: In Africa and Asia, sugarcane is the host of at least seven different virus species in the genus Mastrevirus of the family Geminiviridae. However, with the exception of Sugarcane white streak virus in Barbados, no other sugarcane-infecting mastrevirus has been reported in the New World. Conservation and exchange of sugarcane germplasm using stalk cuttings facilitates the spread of sugarcane-infecting viruses. METHODS: A virion-associated nucleic acids (VANA)-based metagenomics approach was used to detect mastrevirus sequences in 717 sugarcane samples from Florida (USA), Guadeloupe (French West Indies), and Réunion (Mascarene Islands). Contig assembly was performed using CAP3 and sequence searches using BLASTn and BLASTx. Mastrevirus full genomes were enriched from total DNA by rolling circle amplification, cloned and sequenced. Nucleotide and amino acid sequence identities were determined using SDT v1.2. Phylogenetic analyses were conducted using MEGA6 and PHYML3. RESULTS: We identified a new sugarcane-infecting mastrevirus in six plants sampled from germplasm collections in Florida and Guadeloupe. Full genome sequences were determined and analyzed for three virus isolates from Florida, and three from Guadeloupe. These six genomes share >88% genome-wide pairwise identity with one another and between 89 and 97% identity with a recently identified mastrevirus (KR150789) from a sugarcane plant sampled in China. Sequences similar to these were also identified in sugarcane plants in Réunion. CONCLUSIONS: As these virus isolates share <64% genome-wide identity with all other known mastreviruses, we propose classifying them within a new mastrevirus species named Sugarcane striate virus. This is the first report of sugarcane striate virus (SCStV) in the Western Hemisphere, a virus that most likely originated in Asia. The distribution, vector, and impact of SCStV on sugarcane production remains to be determined.
Assuntos
Geminiviridae/classificação , Geminiviridae/isolamento & purificação , Saccharum/virologia , Clonagem Molecular , Análise por Conglomerados , DNA Viral/química , DNA Viral/genética , DNA Viral/isolamento & purificação , Florida , Guadalupe , Filogenia , Reunião , Análise de Sequência de DNA , Homologia de Sequência , Sequenciamento Completo do GenomaRESUMO
Thirty-five unique partial sugarcane bacilliform virus (SCBV) sequences extending over 529 bp were identified in sugarcane samples from Guadeloupe diagnosed by Immunocapture-PCR (IC-PCR) using specific badnavirus primers. Phylogenetic analysis of these sequences along with the two known genome sequences of Sugarcane bacilliform Mor virus (SCBMV) and Sugarcane bacilliform IM virus (SCBIMV) revealed high molecular variability in the SCBV genome. Seven phylogenetic groups, named A to G, were characterized: virus isolates from groups A-B, C and D are proposed to be members of three additional SCBV species. The two (7446 and 7444 bp) and one (7317 bp) complete sequences of SCBV isolates from groups A and D, respectively, likely represented the genome of two new species. Phylogenetic analysis of the complete genome and RT/RNase H sequences confirmed the polyphyletic structure of SCBV isolates and the absence of a clear separation between SCBV and Banana streak virus (BSV) isolates within badnavirus group 1. These results showed that reconsideration of taxonomy and classification of SCBV and BSV are necessary.